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Date: Tue, 31 Aug 2004 16:24:08 -0700
From: Andrew Morton <akpm@osdl.org>
To: Hiroyuki KAMEZAWA <kamezawa.hiroyu@jp.fujitsu.com>
Cc: haveblue@us.ibm.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org,
       lhms-devel@lists.sourceforge.net
Subject: Re: [Lhms-devel] Re: [RFC] buddy allocator without bitmap(2) [0/3]
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Hiroyuki KAMEZAWA <kamezawa.hiroyu@jp.fujitsu.com> wrote:
>
> Because I had to record some information about shape of mem_map, I used PG_xxx bit.
> 1 bit is maybe minimum consumption.

The point is that we're running out of bits in page.flags.

You should be able to reuse an existing bit for this application.  PG_lock would suit.